Ohmic Contact-Free Mobility Measurement in Ultra-Wide Bandgap AlGaN/AlGaN Devices

We measure the electron density dependence of carrier mobility in ultra-wide bandgap Al0.85Ga0.15N/Al0.7Ga0.3N heterostructures, using only Au/Pt Schottky contact deposition and without the need for Ohmic contacts. With this technique, we measure mobility over a two-dimensional electron gas density range from 10(10) to 10(13) cm(-2) at an AlGaN/AlGaN heterojunction. At room temperature, subthresholdmobility was 4 cm(2)/Vs and peakmobility 155 cm(2)/Vs. Peak mobility decreased with temperature as T-0.86 suggesting alloy scattering as the dominant scattering mechanism.